diff --git a/lib/hx509/crypto.c b/lib/hx509/crypto.c
index 87bf55537..c5372c9c8 100644
--- a/lib/hx509/crypto.c
+++ b/lib/hx509/crypto.c
@@ -408,7 +408,7 @@ ecdsa_create_signature(hx509_context context,
     int ret;
 
     if (der_heim_oid_cmp(signer->ops->key_oid, &asn1_oid_id_ecPublicKey) != 0)
-	return HX509_ALG_NOT_SUPP;
+	_hx509_abort("internal error passing private key to wrong ops");
 
     sig_oid = sig_alg->sig_oid;
     digest_alg = sig_alg->digest_alg;